Management's Impact on Osteochondral Lesion Development

Do you bed your young horses down in stalls in the winter? How smooth and flat are your pastures? When you’re trying to raise good bones and joints, these questions are worth considering. Because, according to French researchers, how you manage your young stock can have a direct effect on how osteochondral lesions evolve—for better or for worse.

According to recent study results, pasturing horses on rough terrain and stabling horses up at night are risk factors for worsening juvenile osteochondral conditions (JOCCs) in horses between ages 6 and 18 months, said Anne Praud, PhD, researcher at the Alfort National Veterinary School in Maisons-Alfort.

Praud and her fellow researchers collected radiographic and farm management data for 259 yearlings born on 20 different stud farms in Normandy, France. They compared the JOCC lesions and severity in six-month radiographs (X rays) to those taken at 18-months. Then the team investigated links between the way the horses were managed and how their JOCC scores evolved over the one-year period. The study was a part of the larger Breeding, Osteochondral Status, and Athletic Career (BOSAC) research program led by Jean-Marie Denoix, DVM, PhD, Dipl. ACVSMR, director of the Centre d'Imagerie et de Recherche sur les Affections Locomotrices Equines (CIRALE) in Goustranville (Normandy), France.

The primary risk factors for a worsening JOCC score were related to traumatic injuries and biomechanical stress, Praud said. And horses kept on uneven pasture ground tended to have JOCC scores that worsened over time.

But, perhaps surprisingly for some breeders, between stabling horses in the barn at night and a worsening score. That’s probably not so much due to nighttime inactivity as it is “violent” activity in the morning when horses are turned out, she added.

“They just tend to ‘explode’ into the air when they get out in the mornings,” said Praud. “And often that’s onto a frozen ground or a very muddy ground (which can lead to accidents and slips). So the best thing to do in that case is to not let them out too abruptly but to allow them to have a more progressive movement.”

Ensuring that horses stay in stable groups can also reduce risk, she said, as there will not be a lot of violent activity related to establishing hierarchy.

Another important risk factor she found was the existence of a severe lesion at 6 months old, Praud said. If the lesion is already severe at that age, it tends to worsen by the time the horse reaches 18 months of age, so extra care should be taken for these foals.

“The (JOCC score) at six months should therefore be taken into account by breeders and encourage them to adapt the management of those foals that are already affected by JOCC between six and 17 months,” Praud said.

While the study and other studies in the BOSAC program appeared initially to suggest that there was a difference in breeds with regard to JOCC, Praud said this can be explained by a difference in management techniques among the breeders. Even so, breed does seem to account for the appearance of JOCC lesions in weanlings.

“Our hypothesis is that breed plays a part in the development of JOCC in young foals, but that its impact lessens after 6 months of age,” she said.